[SCTP] Flag a pmtu change request

Currently, if the socket is owned by the user, we drop the ICMP
message.  As a result SCTP forgets that path MTU changed and
never adjusting it's estimate.  This causes all subsequent
packets to be fragmented.  With this patch, we'll flag the association
that it needs to udpate it's estimate based on the already updated
routing information.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Acked-by: Sridhar Samudrala <sri@us.ibm.com>
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index dc0e70c..ee4559b 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -912,6 +912,9 @@
 	 */
 	__u16 pathmaxrxt;
 
+	/* is the Path MTU update pending on this tranport */
+	__u8 pmtu_pending;
+
 	/* PMTU	      : The current known path MTU.  */
 	__u32 pathmtu;
 
@@ -1566,6 +1569,9 @@
 	 */
 	__u16 pathmaxrxt;
 
+	/* Flag that path mtu update is pending */
+	__u8   pmtu_pending;
+
 	/* Association : The smallest PMTU discovered for all of the
 	 * PMTU	       : peer's transport addresses.
 	 */